DALLAS April 24, 2014 Scientific research at UT Southwestern Medical Center previously discovered that the newborn animal heart can heal itself completely, whereas the adult heart lacks this ability. New research by the same team today has revealed why the heart loses its incredible regenerative capability in adulthood, and the answer is quite simple oxygen.
Yes, oxygen. It is well-known that a major function of the heart is to circulate oxygen-rich blood throughout the body. But at the same time, oxygen is a highly reactive, nonmetallic element and oxidizing agent that readily forms toxic substances with many other compounds. This latter property has now been found to underlie the loss of regenerative capacity in the adult heart.
This groundbreaking new finding, published in today's issue of Cell, finds that the oxygen-rich postnatal environment results in cell cycle arrest of cardiomyocytes, or heart cells.
"Knowing the key mechanism that turns the heart's regenerative capacity off in newborns tells us how we might discover methods to reawaken that capacity in the adult mammalian heart," said Dr. Hesham Sadek, Assistant Professor of Internal Medicine at UT Southwestern and senior author of the study.
Due to the oxygen-rich atmosphere experienced immediately after birth, heart cells build up mitochondria the powerhouse of the cell which results in increased oxidization. The mass production of oxygen radicals by mitochondria damages DNA and, ultimately, causes cell cycle arrest.
"We have uncovered a previously unrecognized protective mechanism that mediates cardiomyocyte cell cycle arrest and that arises as a consequence of oxygen-dependent aerobic metabolism," said Dr. Sadek.
Physiologically speaking, Dr. Sadek said, mammals likely had to make the choice early on between being energy efficient or retaining
|Contact: Lisa Warshaw|
UT Southwestern Medical Center